A new map, Santa's Evil Lair, will overflow with special yuletide versions of Killing Floor's genetic monstrosities, from gingerbread men and elves to Jack Frost and Big S himself. There'll also be also new achievements and an unlockable 'Baddest Santa' player skin.

On top of all that, players who also own Team Fortress 2 will be able to play as the Pyro in Killing Floor and score a 'Mr Fosters Gasmask and Tie' item to wear back in TF2.

The Twisted Christmas event will kick off on December 14, running until January 4.